My reading of Make Way for Ducklings is not seeped in nostalgia like some readers' experiences might be at a later age. Because of this, I might have the advantage (or disadvantage?) of recognizing some questionable plot holes that the more sentimental reader might overlook.
Mr. and Mrs. Mallard open our story by flying over beautiful New England scenery with plenty of lakes, woods, and fields looking for a place to raise their family. Because there might be natural predators in, well, nature, they press onward toward the (naturally) safer choice to raise babies: in the heart of an east cost Metropolis.
Landing on an island in a lake in the middle of a city park, The Mallards delight in the free peanuts city slickers toss at them and exclaim that this right here is the good life (note: ducks should not eat peanuts). That is, until they almost get run over by a bicycle. No good! We can't have our babies squished. Let's press on, they agree.
Spotting another island (this time in the Charles River), The Mallards make the split-second decision of, "Yes let's just stay here." Good thing! Cause those eggs be comin.
The Mallards hang at their new island home, occasionally paddling over to the mainland to hang with their new police officer friend, Michael, who, you guessed it, feeds them peanuts.